From various control and security systems, computer-controlled devices are known which comprise a lock device and a key device for opening said lock device. The key device comprises an identification code which is read by the system by using a reading device and which is used by the system to identify the key device and to control the lock device to open. By means of the control, it is possible in a programmed manner to prevent or allow the use of a certain key device and to enter new key devices in the system. For example, card-like key devices are known which contain a printed, readable bar code for the identification code.
In control systems, also transceivers are used, such as transponders, which contain an individual identification code stored in a read-only memory (ROM). Thus, the identification code is only readable, but transceivers may also contain a random access memory (RAM) for storing variable data. The reading device transmits a signal to the transceiver, e.g. a passive transponder, by means of an inductive coupling. This signal is transmitted, by means of the inductive coupling and after being modulated according to the identification code in the key device, back to the reading device. The typical reading distance of the reading device extends to about 0.1 meters. To some transponders, the reading device transmits a microwave frequency radio signal which is transmitted, after being modulated with the identification code, from the antenna of the transponder back to the reading device. The typical reading distance of the reading device extends to about 4.0 meters, and the reading device can identify several identifications at a time, but the identification also contains a power supply, such as a battery.
Known conventional lock and key devices also include a mechanical lock and key for buildings as well as an infrared transmitter for vehicles, such as automobiles, which is fitted in a mechanical key and which transmits a standardized encoded infrared signal, when needed. The code contained in said signal is received, identified, and the electrical locking system of the automobile releases the locking of the doors and often also releases the immobiliser system. For buildings is also known an electrical locking system which comprises a keypad and an electrically controlled lock device fitted next to a door. By means of the keypad, a code number is entered in the computer-controlled system and is identified, and if the code number is correct, the locking of the door is released and entry via the door is allowed.
However, the use of separate portable keys involves the problem of arranging the delivery of the keys in an efficient way, particularly supplying and dispatching of keys quickly to users or user groups as well as the returning of keys from the users. In particular, it is difficult to quickly serve persons who are occasionally or temporarily in need of keys. The return of borrowed keys to prevent their later use is uncertain and causes delays. Moreover, keys can be copied and used later without an authorization. In addition to this, the manufacture of the keys involves costs and time delays.
Separate keys can be abandoned by giving the users code numbers which are entered via a keypad to a control system. Problems are also involved in arranging the delivery of code numbers, particularly the safe and correct delivery of the code numbers to the users. Similarly, it may be difficult to keep the code numbers safely with the users, and memory-based safekeeping is uncertain. Moreover, as a result of the abundance of information related to the code number, such as encryption and confirmation, as well as the abundance of required code combinations, the length of the code numbers is increased, wherein also the risk of errors in their manual entry and use is increased.